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  1. Marzaioli, Fabio (Ed.)
    Unidentified human remains have historically been investigated nationally by law enforcement authorities. However, this approach is outdated in a globalized world with rapid transportation means, where humans easily move long distances across borders. Cross-border cooperation in solving cold-cases is rare due to political, administrative or technical challenges. It is fundamental to develop new tools to provide rapid and cost-effective leads for international cooperation. In this work, we demonstrate that isotopic measurements are effective screening tools to help identify cold-cases with potential international ramifications. We first complete existing databases of hydrogen and sulfur isotopes in human hair from residents across North America by compiling or analyzing hair from Canada, the United States (US) and Mexico. Using these databases, we develop maps predicting isotope variations in human hair across North America. We demonstrate that both δ 2 H and δ 34 S values of human hair are highly predictable and display strong spatial patterns. Multi-isotope analysis combined with dual δ 2 H and δ 34 S geographic probability maps provide evidence for international travel in two case studies. In the first, we demonstrate that multi-isotope analysis in bulk hair of deceased border crossers found in the US, close to the Mexico-US border, help trace their last place of residence or travel back to specific regions of Mexico. These findings were validated by the subsequent identification of these individuals through the Pima County Office of the Medical Examiner in Tucson, Arizona. In the second case study, we demonstrate that sequential multi-isotope analysis along the hair strands of an unidentified individual found in Canada provides detailed insights into the international mobility of this individual during the last year of life. In both cases, isotope data provide strong leads towards international travel. 
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  2. Stable isotope ratios of hydrogen and oxygen have been applied to water cycle research for over 60 years. Over the past two decades, however, new data, data compilations, and quantitative methods have supported the application of isotopic data to address large-scale water cycle problems. Recent results have demonstrated the impact of climate variation on atmospheric water cycling, provided constraints on continental- to global-scale land-atmosphere water vapor fluxes, revealed biases in the sources of runoff in hydrological models, and illustrated regional patterns of water use and management by people. In the past decade, global isotopic observations have spurred new debate over the role of soils in the water cycle, with potential to impact both ecological and hydrological theory. Many components of the water cycle remain underrepresented in isotopic databases. Increasing accessibility of analyses and improved platforms for data sharing will refine and grow the breadth of these contributions in the future. ▪ Isotope ratios in water integrate information on hydrological processes over scales from cities to the globe. ▪ Tracing water with isotopes helps reveal the processes that govern variability in the water cycle and may govern future global changes. ▪ Improvements in instrumentation, data sharing, and quantitative analysis have advanced isotopic water cycle science over the past 20 years. 
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  3. Abstract. The hydrogen and oxygen stable isotope ratios of water have been used to identify sources, transport pathways, and phase-change processes within the water cycle, supporting hydrologic, forensic, ecologic, and hydroclimatic investigations. Here, we introduce a unique, open-access, global database of stable water isotope ratios (δ18O, δ17O, and δ2H) from various water types. This database facilitates data preservation, supports standardized metadata collection, and decreases the time investment for meta-analytic research and reference dataset discovery. As of July 2019, the database includes 231 586 samples from 52 210 sites, associated with 218 projects, spanning 1949 through 2019. Key information stored includes the hydrogen and oxygen isotope ratios, water type, collection date and time, site location, and project information. To promote rapid data discovery and collaboration, the database exposes metadata such as data owner contact information of embargoed data, but only permits downloads of public data. The database is supported by two companion apps, one for processing and upload of analytical data from laboratories and the other an iOS application that supports the digital collection of sample metadata. 
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